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Brucellosis in Cattle; State and Area Classifications; Idaho

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Animal and Plant Health Inspection Service, USDA.


Affirmation of interim rule as final rule.


We are adopting as a final rule, without change, an interim rule that amended the brucellosis regulations concerning interstate movement of cattle by changing the classification of Idaho from Class Free to Class A. That action was necessary to prevent the interstate spread of brucellosis.


Effective on June 29, 2006, we are adopting as a final rule the interim rule that became effective on January 12, 2006.

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Dr. Debra Donch, National Brucellosis Epidemiologist, National Center for Animal Health Programs, VS, APHIS, 4700 River Road Unit 43, Riverdale, MD 20737-1231; (301) 734-6954.

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Brucellosis is a contagious disease caused by bacteria of the genus Brucella. The brucellosis regulations, contained in 9 CFR part 78 (referred to below as the regulations), provide a system for classifying States or portions of States according to the rate of Brucella infection present and the general effectiveness of a brucellosis control and eradication program. The classifications are Class Free, Class A, Class B, and Class C. States or areas that do not meet the minimum standards for Class C are required to be placed under Federal quarantine.

In an interim rule [1] effective January 12, 2006, and published in the Federal Register on January 19, 2006 (71 FR 2991-2993, Docket No. APHIS-2006-0001), we amended § 78.41 of the regulations by changing the classification of Idaho from Class Free to Class A. That action was necessary to prevent the interstate spread of brucellosis.

Comments on the interim rule were required to be received on or before March 20, 2006. We received two comments by that date. One comment was from a private citizen who questioned why the affected cattle had not been vaccinated for brucellosis. Although vaccination can be effective to some degree in preventing the transmission and spread of the Brucella bacteria, it is not 100 percent effective; therefore, disease transmission may still occur even though a herd is vaccinated. The commenter also objected to cattle being allowed to graze on publicly owned land. This issue is not within the scope of the interim rule.

The second comment was from a representative of the Idaho Department of Agriculture, who stated that the Animal and Plant Health Inspection Service (APHIS) should not have changed Idaho's brucellosis status from Class Free to Class A because the second affected herd was the result of the movement, from the first affected herd, of a heifer that was subsequently classified as a reactor. According to the commenter, the heifer cannot positively be diagnosed with brucellosis because the heifer tested positive for Yersinia, because no Brucella organism was cultured from the heifer's tissues, because the cow was vaccinated with RB51, which could cause false positives in brucellosis testing in some cases, and because the heifer was not pregnant and there are no studies proving that a heifer that is not pregnant may pass along the brucellosis bacteria through bodily discharge of wastes.

The regulations define an affected herd as “Any herd in which any animal has been classified as a brucellosis reactor and which has not been released from quarantine.” Both herds designated as affected herds in Idaho contained at least one animal that was classified by the State's designated brucellosis epidemiologist as a brucellosis reactor.

The State's designated brucellosis epidemiologist classified the heifer as a brucellosis reactor based on that fact that it originated from an infected herd and based on a panel of positive serological test results, which were repeated in both State and Federal laboratories. Culture confirmation of reactors is not 100 percent successful in all brucellosis cases and therefore is not required under the regulations for classification of infected animals. Although Yersinia, another bacteria found in cattle, may cause false positive results on a serologic test for Brucella, most of these tests are not able to differentiate Brucella from Yersinia. Currently there is no conclusive evidence that the RB51 vaccine caused the positive results on the serology tests for Brucella.

Although the probability of brucellosis exposure from a virgin heifer is lower than from a pregnant heifer because the primary method of transmission of brucellosis is usually via an infected, aborted fetus, an infected newborn calf, and/or infected tissues and fluids that accompany a birth event, transmission of brucellosis via the urine and feces of infected animals is also possible.

In addition, State status is based on herd infection rates, not on the likelihood of disease transmission. The regulations specifically state that to qualify for Class Free status, a State “must have a cattle herd infection rate, based on the number of herds found to have brucellosis reactors within the State or area during any 12 consecutive months due to field strain Brucella abortus of 0.0 percent or 0 herds per 1,000.” Idaho has exceeded the criteria of 0.0 percent herd infection rate according to the regulations. Idaho also does not qualify for retaining its Class Free status because more than one herd has been found to be affected with brucellosis during a 2-year period.

Therefore, for the reasons given in the interim rule and in this document, we are adopting the interim rule as a final rule without change. This action also affirms the information contained in the interim rule concerning Executive Order 12866 and the Regulatory Flexibility Act, Executive Orders 12372 and 12988, and the Paperwork Reduction Act.

Further, for this action the Office of Management and Budget has waived its review under Executive Order 12866.

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List of Subjects in 9 CFR Part 78

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Accordingly, we are adopting as a final rule, without change, the interim rule that amended

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Done in Washington, DC, this 23rd day of June 2006.

Kevin Shea,

Acting Administrator, Animal and Plant Health Inspection Service.

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1.  To view the interim rule and the comments we received, go to, click on the “Advanced Search” tab, and select “Docket Search.” In the Docket ID field, enter APHIS-2006-0001, then click on “Submit.” Clicking on the Docket ID link in the search results page will produce a list of all documents in the docket.

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[FR Doc. 06-5800 Filed 6-28-06; 8:45 am]